Abstract:

A wireless transceiver for transmitting data across a pipe joint is
described herein. At least some illustrative embodiments include a
wireless communication apparatus including a housing configured to be
positioned inside/proximate of/to an end of a drill pipe. The housing
includes an antenna with at least one RF signal propagation path parallel
to the axis of the housing, and an RF module (coupled to the antenna)
configured to couple to a communication cable, and to provide at least
part of a data retransmission function between an antenna signal and a
communication cable signal. A material (transparent to RF signals within
the RF module's operating range) is positioned along the circumference,
and at/near an axial end, of the housing closest to the antenna. At least
some RF signals, axially propagated between the antenna and a region near
said axial end, traverse the radiotransparent material along the
propagation path.

Claims:

1. A wireless communication apparatus, comprising:a housing configured to
be positioned inside of, and proximate to an end of, a drill pipe
suitable for use as part of a drill string, the housing comprising:an
antenna configured such that at least one radio frequency (RF) signal
propagation path of the antenna is substantially parallel to the central
axis of the housing; andan RF module coupled to the antenna and
configured to couple to a communication cable, wherein the RF module is
configured to provide at least part of a data retransmission function
between an RF signal present on the antenna and a data signal present on
the communication cable;wherein a radiotransparent material, which is
transparent to RF signals within the operating frequency range of the RF
module, is positioned along the circumference, and at or near an axial
end, of the housing that is most proximate to the antenna; andwherein at
least some axially propagated RF signals, which pass between the antenna
and a region axially proximate to said axial end of the housing, pass
through the radiotransparent material along said at least one RF signal
propagation path.

2. The wireless communication apparatus of claim 1, wherein the
radiotransparent material comprises a material selected from the group
consisting of a fiber-reinforced polymer and a silicone rubber.

3. The wireless communication apparatus of claim 1, wherein the at least
one RF signal propagation path is also substantially parallel to an
H-plane associated with the antenna.

4. The wireless communication apparatus of claim 1,wherein the RF module
comprises an RF transmitter; andwherein the RF transmitter is configured
to receive data encoded within the data signal present on the
communication cable, and further configured to retransmit the data by
generating and modulating the RF signal present on the antenna.

5. The wireless communication apparatus of claim 1,wherein the RF module
comprises an RF receiver that receives the RF signal present on the
antenna; andwherein the RF module extracts and retransmits data encoded
within the received RF signal for inclusion within the data signal
present on the communication cable.

6. The wireless communication apparatus of claim 1, wherein the
radiotransparent material is integrated within the housing.

7. The wireless communication apparatus of claim 1, further comprisinga
spacer configured to be positioned inside, and proximate to the end of,
the drill pipe;wherein at least part of the spacer comprises the
radiotransparent material and is positioned along the circumference, and
axially adjacent to an exterior surface, of the end of the housing most
proximate to the antenna.

8. The wireless communication apparatus of claim 1, further comprising:one
or more batteries that couple and provide power to the RF module; anda
power source module that couples to and charges the one or more
batteries;wherein the power source module comprises a power source
selected from the group consisting of a kinetic microgenerator, a thermal
microgenerator and a wireless energy transfer power source.

9. The wireless communication apparatus of claim 1, wherein the antenna
comprises a type of antenna selected from the group consisting of a spike
antenna and a loop antenna.

10. A wireless communication system, comprising:one or more radio
frequency radio frequency (RF) transceivers, each RF transceiver housed
within a housing that is configured to be positioned inside, and
proximate to an end, of a drill pipe within a drill string, and each RF
transceiver configured to be coupled by a communication cable to a
downhole device positioned within the same drill pipe;one or more
antennas, each antenna coupled to a corresponding RF transceiver of the
one or more RF transceivers, each antenna housed within the same housing
as the corresponding RF transceiver and each antenna configured such that
at least one RF signal propagation path of the antenna is substantially
parallel to the central axis of said same housing; andone or more
radiotransparent spacers that are transparent to RF signals within the
operating frequency range of the one or more RF transceivers, each
radiotransparent spacer positioned along the circumference, and at or
near an axial end, of a corresponding housing that is most proximate to
the antenna within the said corresponding housing;wherein a first RF
signal is received by a first antenna of the one or more antennas through
a first radiotransparent spacer of the one or more radiotransparent
spacers, the first antenna coupled to a first RF transceiver of the one
or more transceivers that extracts receive data from the first RF signal
and retransmits the receive data for inclusion in a first data signal
transmitted to the downhole device over the data communication cable.

11. The wireless communication system of claim 10, wherein the
radiotransparent one or more radio transparent spacers are formed at
least in part using a material that comprises a material selected from
the group consisting of a fiber-reinforced polymer and a silicone rubber.

12. The wireless communication system of claim 10,wherein the first
radiotransparent spacer, corresponding to a first housing comprising the
first RF transceiver, is axially adjacent to a second radiotransparent
spacer of the one or more radiotransparent spacers that corresponds to a
second housing comprising a second RF transceiver of the one or more
transceivers; andwherein the second RF transceiver transmits via a second
antenna of the one or more antennas the first RF signal received by the
first RF transceiver via the first antenna, at least part of the first RF
signal propagating from the second antenna, through both the first and
second radiotransparent spacers, and to the first antenna along the at
least one RF signal propagation path of the first antenna.

13. The wireless communication system of claim 12, wherein the propagation
path is also substantially parallel to an H-plane associated with at
least one of the first and second antennas.

14. The wireless communication system of claim 12, wherein the magnitude
of the first RF signal present on the first antenna is substantially
independent of the radial orientation of the first antenna relative to
the radial orientation of the second antenna.

15. The wireless communication system of claim 10, wherein the downhole
device comprises at least one device selected from the group consisting
of a third RF transceiver of the one or more transceivers, a measurement
while drilling (MWD) device, a logging while drilling (LWD) device, and a
drill bit steering control device.

16. The wireless communication system of claim 10, wherein each
radiotransparent spacer is integrated within each corresponding housing.

17. A drill pipe used as part of a drill string, comprising:at least one
housing that is positioned inside of, and proximate to, one of two ends
of the drill pipe, the at least one housing comprising:an antenna
configured such that at least one radio frequency (RF) signal propagation
path is substantially parallel to the central axis of the drill pipe;
andan RF module coupled to the antenna and to a downhole device within
the drill pipe;a communication cable that couples the RF module to the
downhole device, the RF module providing at least part of a
retransmission function between a data signal present on the
communication cable and an RF signal present on the antenna; andat least
one radiotransparent spacer that is transparent to RF signals within the
operating frequency range of the RF module, and that is positioned along
the circumference of, and at or near an axial end of, the at least one
housing, said axial end being an end most proximate to the
antenna;wherein at least some axially propagated RF signals, which pass
between the antenna and a region axially proximate to the axial end of
the corresponding housings, pass through the radiotransparent spacer
along the at least one RF signal propagation path.

18. The drill pipe of claim 17, wherein the at least one radiotransparent
spacer is formed at least in part using a material that comprises a
material selected from the group consisting of a fiber-reinforced polymer
and a silicone rubber.

19. The drill pipe of claim 17, wherein the at least one RF signal
propagation path is also substantially parallel to an H-plane associated
with the antenna.

20. The drill pipe of claim 17, further comprising:a first housing of the
at least one housing, further comprising a first data processing module
coupled to a first RF module that further comprises an RF receiver
coupled to a first antenna; anda second housing of the at least one
housing, the downhole device comprising the second housing, and the
second housing further comprising a second data processing module coupled
to a second RF module that further comprises an RF transmitter coupled to
a second antenna, the first and second data processing modules coupled to
each other by the communication cable;wherein the RF receiver extracts
data encoded within a first RF signal received by the RF receiver and
provides the data to the first data processing module, which formats and
encodes the data within the data signal and transmits the data signal
over the communication cable to the second data processing module;
andwherein the second data processing module extracts the data from the
data signal received from the first data processing module and provides
the data to the RF transmitter, which uses the data to modulate and
transmit a second RF signal.

21. The drill pipe of claim 17, the at least one housing further
comprising a data processing module coupled to the RF module, and the RF
module further comprising an RF receiver and an RF transmitter that are
both coupled to the antenna;wherein the RF receiver extracts receive data
encoded within the RF signal received by the RF receiver and provides the
receive data to the data processing module, which formats and encodes the
receive data within the a first data signal and transmits the first data
signal over the communication cable to the downhole device; andwherein
the data processing module extracts transmit data encoded within a second
data signal received from the downhole device and provides the transmit
data to the RF transmitter, which uses the transmit data to modulate and
transmit a second RF signal.

22. The drill pipe of claim 21, wherein the downhole device comprises at
least one device selected from the group consisting of a measurement
while drilling (MWD) device, a logging while drilling (LWD) device, and a
drill bit steering control device.

23. The drill pipe of claim 17, wherein the communication cable comprises
an electrical conductor, and the data signal present on the communication
cable comprises an electrical signal.

24. The drill pipe of claim 17, wherein the communication cable comprises
a fiber optic cable, and the data signal present on the communication
cable comprises an optical signal.

25. A drill string, comprising:a plurality of drill pipes, each drill pipe
mechanically coupled to at least one other drill pipe to form the drill
string, and each drill pipe comprising:at least one housing of a
plurality of housings that is positioned inside of, and proximate to, one
of two ends of the drill pipe, the at least one housing comprising:an
antenna configured such that at least one radio frequency (RF) signal
propagation path is substantially parallel to the central axis of the
drill pipe; andan RF transceiver coupled to the antenna;a downhole device
positioned inside the drill pipe;a communication cable that couples the
RF transceiver of the at least one housing to the downhole device,
wherein the RF transceiver provides at least part of a retransmission
function between a data signal present on the communication cable and an
RF signal present on the antenna; andat least one radiotransparent spacer
that is transparent to RF signals within the operating frequency range of
the RF transceiver, and is positioned along the circumference of, and at
or near an axial end of, the at least one housing, said axial end being
an end most proximate to the antenna;wherein a first end of a first drill
pipe is mechanically coupled to a second end of a second drill pipe, a
first housing of the at least one housing of the first drill pipe
positioned within the first end, and the at least one housing of the
second drill pipe positioned within the second end; andwherein at least
some axially propagated RF signals that pass between the antennas of the
first and second drill pipes, also pass through the radiotransparent
spacers of both the first and second drill pipes along the at least one
RF signal propagation path.

26. The drill string of claim 25, wherein the at least one
radiotransparent spacer is formed at least in part using a material that
comprises a material selected from the group consisting of a
fiber-reinforced polymer and a silicone rubber.

27. The drill string of claim 25, wherein the at least one RF signal
propagation path is also substantially parallel to an H-plane associated
with at least one of the antennas of the first and second drill pipes.

28. The drill string of claim 25, wherein the magnitude of an RF signal
present on the antenna of the first drill pipe is substantially
independent of the radial orientation of the antenna of the first drill
pipe relative to the radial orientation of the antenna of the second
drill pipe.

29. The drill string of claim 25, each of the at least one housing further
comprising a data processing module coupled to, and in between, the RF
transceiver and the data communication cable;wherein the downhole device
of the first drill pipe generates the data signal present on the
communication cable of the first drill pipe and further encodes data
within the data signal of the first drill pipe, which is received by the
data processing module of the first housing; andwherein the data
processing module of the first housing extracts the data from the data
signal of the first drill pipe and provides the data to the RF
transceiver of the first housing, which modulates with the data, and
transmits, the RF signal present on the antenna of the first housing.

30. The drill string of claim 25, each of the at least one housing further
comprising a data processing module coupled to, and in between, the RF
transceiver and the data communication cable;wherein the RF transceiver
of the first housing extracts data from the RF signal present on the
antenna of the first housing and further provides the data to the data
processing module of the first housing; andwherein the data processing
module of the first housing encodes the data within the data signal
present on the communication cable of the first drill pipe and transmits
the data signal of the first drill pipe to the downhole device of the
first drill pipe.

31. The drill string of claim 25, wherein the downhole device of the first
drill pipe comprises at least one device selected from the group
consisting of a data processing module within a second housing of the at
least one housing, a measurement while drilling (MWD) device, a logging
while drilling (LWD) device, and a drill bit steering control device.

32. The drill string of claim 25, wherein the communication cable
comprises a cable selected from the group consisting of an electrical
cable and an optical cable.

33. A method for wireless transmission of data across a joint mechanically
connecting two drill pipes within a drill string, comprising:receiving,
by a radio frequency (RF) transmitter at or near a first end of a first
drill pipe, data across a cable from a first device within the first
drill pipe;the RF transmitter modulating an RF signal using the data
received;the RF transmitter transmitting the modulated RF signal using a
first antenna, through a first radiotransparent material, and across the
joint mechanically connecting the first drill pipe to a second drill
pipe;propagating the RF signal along an RF signal propagation path
substantially parallel to the central access of at least one of the two
drill pipesreceiving, by an RF receiver using a second antenna at or near
a second end of a second drill pipe, the modulated RF signal through a
second radiotransparent material along said RF signal propagation path,
the first and second radiotransparent materials both positioned in a
space within the joint between the first antenna and the second
antenna;the RF receiver extracting the data from the modulated RF signal;
andthe RF receiver transmitting the data across a cable to a second
device within the second drill pipe.

34. The method of claim 33, wherein the first and second radiotransparent
materials each comprises a material selected from the group consisting of
a fiber-reinforced polymer and a silicone rubber.

35. The method of claim 33, wherein the propagating the RF signal further
comprises propagating along a path that is also substantially parallel to
an H-plane associated with at least one of the antennas of the first and
second drill pipes

36. The method of claim 33, further comprising using the data to control
at least part of the operation of the drill string.

37. The method of claim 33, further comprising using the data to monitor
at least part of the operation of the drill string.

38. The method of claim 33,wherein the first device comprises at least one
device selected from the group consisting of another RF receiver, a
measurement while drilling (MWD) device, a logging while drilling (LWD)
device, and a drill bit steering control device; andwherein the second
device comprises at least one device selected from the group consisting
of another RF transmitter, a measurement while drilling (MWD) device, a
logging while drilling (LWD) device, and a drill bit steering control
device.

Description:

BACKGROUND

[0001]As the sophistication and complexity of petroleum well drilling has
increased, so has the demand for comparable increases in the amount of
data that can be received from, and transmitted to, downhole drilling
equipment. The demand for real-time data acquisition from measurement
while drilling (MWD) and logging while drilling (LWD) equipment, as well
as real-time precision control of directional drilling, have created a
corresponding need for high bandwidth downhole systems to transfer such
data between the downhole equipment and surface control and data
acquisition systems.

[0002]There are currently a wide variety of downhole telemetry systems
that are suitable for use in drilling operations. These include both
wireless and wired systems, as well as combinations of the two. Existing
wireless systems include acoustic telemetry systems, mud pulse telemetry
systems, and electromagnetic telemetry systems. In acoustic telemetry
systems, sound oscillations are transmitted through the mud
(hydroacoustic oscillations), through the drill string
(acoustic-mechanical oscillations), or through the surrounding rock
(seismic oscillations). Such acoustic telemetry systems generally require
large amounts of energy and are limited to data rates at or below 120
bits per second (bps). Mud pulse telemetry systems use positive and
negative pressure pulses within the drilling fluid to transmit data.
These systems require strict controls of the injected fluid purity, are
generally limited to data rates of no more than 12 bps, and are not
suitable for use with foam or aerated drilling fluids.

[0003]Electromagnetic telemetry systems include the transmission of
electromagnetic signals through the drill string, as well as
electromagnetic radiation of a signal through the drilling fluid.
Transmission of electromagnetic signals through the drill string is
generally limited to no more than 120 bps, has an operational range that
may be limited by the geological properties of the surrounding strata,
and is not suitable for use offshore or in salty deposits. Data
transmission using electromagnetic radiation through the drilling fluid
(e.g., using radio frequency (RF) signals or optical signals) generally
requires the use of some form of a repeater network along the length of
the drill string to compensate for the signal attenuation caused by the
scattering and reflection of the transmitted signal. Such systems are
frequently characterized by a low signal-to-noise ratio (SNR) at the
receiver, and generally provide data rates comparable to those of mud
pulse telemetry systems.

[0004]Existing wired systems include systems that incorporate a data cable
located inside the drill string, and systems that integrate a data cable
within each drill pipe segment and transmit the data across each pipe
joint. Current wired systems have demonstrated data rates of up to 57,000
bps, and at least one manufacturer has announced a future system which it
claims will be capable of data rates up to 1,000,000 bps. Wired systems
with data cables running inside the drill string, which include both
copper and fiber optic cables, generally require additional equipment and
a more complex process for adding drill pipe segments to the drill string
during drilling operations. Systems that integrate the cable into each
drill pipe segment require pipe segments that are more expensive to
manufacture, but generally such pipe segments require little or no
modifications to the equipment used to connect drill pipe segments to
each other during drilling operations.

[0005]As already noted, pipe segments with integrated data cables must
somehow transmit data across the joint that connects two pipe segments.
This may be done using either wired or wireless communications. Drill
pipe segments that use wired connections generally require contacting
surfaces between electrical conductors that are relatively free of
foreign materials, which can be difficult and time consuming on a
drilling rig. Also, a number of systems using drill pipes with integrated
cables require at least some degree of alignment between pipe segments in
order to establish a proper connection between the electrical conductors
of each pipe segment. This increases the complexity of the procedures for
connecting drill pipes, thus increasing the amount of time required to
add each pipe segment during drilling operations.

[0006]Drill pipe segments with integrated cables that transmit data across
the pipe joint wirelessly include systems that use magnetic field
sensors, inductive coupling, and capacitive coupling. Systems that use
magnetic field sensors, such as Hall Effect sensors, are generally
limited to operating frequencies at or below 100 kHz. Systems that use
inductive coupling currently are generally limited to data rates of no
more than 57,000 bps. Systems using capacitive coupling require tight
seals and tolerances in order to prevent drilling fluid from leaking into
the gap between the pipe segments and disrupting communications. Based on
the forgoing, existing downhole telemetry systems currently appear to be
limited to proven data rates that are below 1,000,000 bps.

SUMMARY

[0007]A wireless transceiver for transmitting data across a drill pipe
joint is described herein. At least some illustrative embodiments include
a wireless communication apparatus that includes a housing configured to
be positioned inside of, and proximate to an end of, a drill pipe used as
part of a drill string. The housing includes an antenna configured such
that at least one radio frequency (RF) signal propagation path is
substantially parallel to the central axis of the housing, and an RF
module coupled to the antenna and configured to couple to a communication
cable (the RF module configured to provide at least part of a data
re-transmission function between an RF signal present on the antenna and
a data signal present on the communication cable). A radiotransparent
material, which is transparent to RF signals within the operating
frequency range of the RF module, is positioned along the circumference,
and at or near an axial end, of the housing that is most proximate to the
antenna. At least some axially propagated RF signals, which pass between
the antenna and a region axially proximate to said axial end of the
housing, pass through the radiotransparent material along the at least
one RF signal propagation path.

[0008]At least some other illustrative embodiments include a wireless
communication system that includes one or more RF transceivers (each
transceiver housed within a housing that is configured to be positioned
inside, and proximate to an end, of a drill pipe within a drill string,
and each transceiver configured to be coupled by a communication cable to
a downhole device positioned within the same drill pipe), one or more
antennas (each antenna coupled to a corresponding RF transceiver of the
one or more RF transceivers, and each antenna housed within the same
housing as the corresponding RF transceiver), and one or more
radiotransparent spacers that are transparent to RF signals within the
operating frequency range of the one or more RF transceivers (each spacer
positioned along the circumference, and at or near an axial end, of a
corresponding housing that is most proximate to the antenna within the
said corresponding housing). A first RF signal is received by first
antenna of the one or more antennas through a first radiotransparent
spacer of the one or more radiotransparent spacers, which is coupled to a
first RF transceiver of the one or more transceivers that extracts
receive data from the first RF signal and retransmits the receive data
for inclusion in a first data signal transmitted to the downhole device
over the data communication cable.

[0009]Other illustrative embodiments include a drill pipe used as part of
a drill string that includes at least one housing (positioned inside of,
and proximate to, one of two ends of the drill pipe), a communication
cable that couples a radio frequency (RF) module to a downhole device
within the drill pipe (the RF module providing at least part of a
retransmission function between a data signal present on the
communication cable and an RF signal present on an antenna) and at least
one radiotransparent spacers (transparent to RF signals within the
operating frequency range of the RF module, and positioned along the
circumference of, and at or near an axial end of, the at least one
housing, said axial end being an end most proximate to the antenna). The
at least one housing includes the antenna (configured such that at least
one RF signal propagation path is substantially parallel to the central
axis of the drill pipe), and the RF module (coupled to the antenna and to
the downhole device). At least some axially propagated RF signals, which
pass between the antenna and a region axially proximate to the axial end
of the corresponding housings, pass through the radiotransparent spacer
along the at least one RF signal propagation path.

[0010]Still other illustrative embodiments include a drill string that
includes a plurality of drill pipes, each drill pipe mechanically coupled
to at least one other drill pipe to form the drill string. Each drill
pipe includes at least one housing of a plurality of housings (positioned
inside of, and proximate to, one of two ends of the drill pipe), a
downhole device positioned inside the drill pipe, a communication cable
that couples a radio frequency (RF) transceiver of the at least one
housing to the downhole device (the RF transceiver providing at least
part of a retransmission function between a data signal present on the
communication cable and an RF signal present on an antenna), and at least
one radiotransparent spacer (transparent to RF signals within the
operating frequency range of the RF transceiver, and positioned along the
circumference of, and at or near an axial end of, the at least one
housing, said axial end being an end most proximate to the antenna). The
at least one housing includes the antenna (configured such that at least
one RF signal propagation path is substantially parallel to the central
axis of the drill pipe), and the RF transceiver (coupled to the antenna).
A first end of a first drill pipe is mechanically coupled to a second end
of a second drill pipe, a first housing of the at least one housing of
the first drill pipe positioned within the first end, and the at least
one housing of the second drill pipe positioned within the second end. At
least some axially propagated RF signals that pass between the antennas
of the first and second drill pipes also pass through the
radiotransparent spacers of both the first and second drill pipes along
the at least one RF signal propagation path.

[0011]Yet other illustrative embodiments include a method for wireless
transmission of data across a joint mechanically connecting two drill
pipes within a drill string, which includes receiving (by a radio
frequency (RF) transmitter at or near a first end of a first drill pipe)
data across a cable from a first device within the first drill pipe; the
RF transmitter modulating an RF signal using the data received, and the
RF transmitter transmitting the modulated RF signal using a first antenna
(through a first radiotransparent material, and across the joint
mechanically connecting the first drill pipe to a second drill pipe). The
method further includes propagating the RF signal along an RF signal
propagation path substantially parallel to the central access of at least
one of the two drill pipes, receiving (by an RF receiver using a second
antenna at or near a second end of a second drill pipe) the modulated RF
signal through a second radiotransparent material (the first and second
radiotransparent material both positioned in a space within the joint
between the first antenna and the second antenna), the RF receiver
extracting the data from the modulated RF signal, and the RF receiver
transmitting the data across a cable to a second device within the second
drill pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]For a detailed description of at least some illustrative
embodiments, reference will now be made to the accompanying drawings in
which:

[0013]FIG. 1 shows a petroleum drilling well in which a communication
apparatus and system constructed in accordance with at least some
illustrative embodiments is employed;

[0014]FIG. 2 shows the drill string of FIG. 1, incorporating wireless
communication assemblies within a communication system constructed in
accordance with at least some illustrative embodiments;

[0015]FIG. 3 shows a block diagram of a wireless communication assembly
constructed in accordance with at least some illustrative embodiments;
and

[0016]FIG. 4A shows a detailed cross-sectional diagram of a drill pipe
joint incorporating a wireless communication assembly constructed in
accordance with at least some illustrative embodiments, which includes a
radiotransparent spacer separate from and attached to the annular
housing;

[0017]FIG. 4B shows a detailed cross-sectional diagram of a drill pipe
joint incorporating a wireless communication assembly constructed in
accordance with at least some illustrative embodiments, which includes an
annular housing made entirely of a radiotransparent material;

[0018]FIG. 5 shows detailed cross-sectional views of the wireless
communication assembly of FIG. 4B, constructed in accordance with at
least some illustrative embodiments;

[0019]FIG. 6 shows a side and top view of a transceiver and antenna
assembly used within the wireless communication assembly of FIG. 5,
constructed in accordance with at least some illustrative embodiments;

[0020]FIG. 7 shows an example of an antenna gain pattern suitable for use
with at least some illustrative embodiments;

[0021]FIG. 8 shows a method for wireless transmission of data across a
joint mechanically connecting two drill pipes within a drill string, in
accordance with at least some illustrative embodiments.

DETAILED DESCRIPTION

[0022]FIG. 1 shows a petroleum drilling rig 100 that incorporates drill
pipes, pipe joints, wireless joint transceivers, and a communication
system, each in accordance with at least some illustrative embodiments. A
derrick 102 is supported by a drill floor 104, and drilling of the
petroleum well is performed by a continuous drill string 111 of drill
pipes 240. The drill pipes 240 are mechanically connected to each other
by joints 200, which each incorporates a wireless transceiver and power
unit (TPU) (not shown) for transmitting and receiving data across the
joint. The drill pipes 240, joints 200 and TPUs are all constructed in
accordance with at least some illustrative embodiments, some of which are
described in more detailed below. A travelling block 106 supports a Kelly
128 at the end of a swivel 129. Kelly 128 connects to the end of drill
string 111, enabling travelling block 106 to raise and lower drill string
111 during drilling operations. In the illustrative embodiment shown,
communications relay transceiver 280 attaches to Kelly 128 at a point
proximate to the TPU at the upper end of drill string 111, and acts as a
wireless communication relay between the wireless communication system
incorporated within drill string 111 and the computer systems (not shown
and also wirelessly communicating with relay 280) used to control and
monitor drilling operations.

[0023]Drill string 111 is raised and lowered through rotary table 122,
which is driven by Motor 124 to rotate drill string 111 and drill bit 116
(connected at the end of drill string 111 together with bottom hole
assembly (BHA) 114). Rotary table 122 provides at least some of the
rotary motion necessary for drilling. In other illustrative embodiments,
swivel 129 is replaced by a top drive (not shown), which rotates drill
string 111 instead of rotary table 122. Additional rotation of drill bit
116 and/or of the cutting heads of the drill bit may also be provided by
a downhole motor (not shown) within or close to drill bit 116. Drilling
fluid or "mud" is pumped by mud pump 136 through supply pipe 135, stand
pipe 134, Kelly pipe 132 and goose necks 130 through swivel 129 and Kelly
128 into drill string 111 at high pressure and volume. The mud exits out
through drill bit 116 at the bottom of wellbore 118, travelling back up
wellbore 118 in the space between the wellbore wall and drill string 111,
and carrying the cuttings produced by drilling away from the bottom of
wellbore 118. The mud flows through blowout preventer (BOP) 120 and into
mud pit 140, which is adjacent to derrick 102 on the surface. The mud is
filtered through shale shakers 142, and reused by mud pump 136 through
intake pipe 138.

[0024]As already noted, drill string 111 incorporates a communication
system constructed in accordance with at least some illustrative
embodiments. Such a communication system, an example of which is shown in
FIG. 2, enables data communication between surface equipment (e.g.,
computer system 300) and downhole equipment (e.g., downhole device 115).
Continuing to refer to FIG. 2, each drill pipe 240 (which for purposes of
this disclosure includes the outer housing 240a of BHA 114) includes a
TPU 246 at one end of the drill pipe, which is coupled to a second
downhole device by a cable 244. In the example of FIG. 2, drill pipes
240d, 240c and 240b each respectively include a TPU 246d, 246c and 246b
(not shown), which each respectively couples via data cable 244d, 244c
and 244b to TPUs (i.e., the downhole devices) 242d, 242c (not shown) and
242b. For BHA 114, TPU 240a couples via cable 244a to downhole device
115. Downhole device 115 may include an MWD device, an LWD device or
drill bit steering control logic, just to name a few examples.

[0025]Data cables 244 can include either copper wire to transmit
electrical signals, or optical fiber to transmit optical signals. Data
cables 244 allow information to be exchanged between the devices (e.g.,
TPUs) within the drill pipes 240. In the example of FIG. 2 the cables are
armored cables that are attached to the inner wall of each corresponding
drill pipe in a coiled pattern that allows for a certain amount of
flexing of the drill pipes. The data cables may be attached to the inner
surface of the drill pipes, or routed through channels cut into the inner
surface of the drill pipes. Many techniques for securing, attaching and
routing cables along and within drill pipes are known to those of
ordinary skill in the art, and such techniques will thus not be discussed
any further. All such techniques are within the scope of the present
disclosure.

[0026]Continuing to refer to FIG. 2 and using an LWD device as an example
of a downhole device 115, logging data is generated by LWD device 115
during drilling operations. The data is formatted and transmitted by LWD
device 115 along data cable 244a to TPU 246a within pipe joint 240a. In
the illustrative embodiment of FIG. 2, the pipe joints 240 of drill
string 111 are pin and box type joints, used to mechanically connect
adjacent drill pipes within drill string 111. BHA 114 includes the box
portion of joint 240a that incorporates TPU 246a, and drill pipe 240b
includes the pin portion of joint 240a that incorporates TPU 242b. TPU
246a receives the data transmitted over data cable 244a by LWD device 115
and wirelessly transmits the data to TPU 242b. TPU 242b in turn receives
the wireless transmission from TPU 246a and reformats and transmits the
received data along data cable 244b to TPU 246b (not shown) at the other
end of drill pipe 240b. The retransmission of data is repeated along each
data cable and wirelessly at each TPU pair (e.g., along data cable 244c
within drill pipe 240c to TPU 246c, wirelessly from TPU 246c to TPU 242d,
and along data cable 244d within drill pipe 240d to TPU 246d).

[0027]Once the data reaches the TPU at the top of drill string 111 (e.g.,
TPU 246d of FIG. 2), the data is wirelessly transmitted to drill string
repeater 282 (part of communications relay transceiver 280), which
couples to external equipment repeater 281 (also part of communications
relay transceiver 280) through Kelly 128 (e.g., via sealed, high pressure
CONex type connectors). External equipment repeater 281 in turn
retransmits the logging data to computer system 300 (e.g., a personal
computer (PC) or other computer workstation) for further processing,
analysis and storage. In the example of FIG. 2 external equipment
repeater 281 communicates with computer system 300 wirelessly, but wired
communication is also contemplated. Many such communications systems for
exchanging data between surface equipment and drill string communication
systems (both wired and wireless) are known within the art, and all such
communications systems are within the scope of the present disclosure.

[0028]In other illustrative embodiments, downhole device 115 includes
drill bit direction control logic for controlling the direction of drill
bit 116. Control data flows in the opposite direction from computer
system 300, through communications relay transceiver 280 to TPU 246d,
across data cable 244d to TPU 242d, and wirelessly to TPU 246c and across
cable 244c. The data is eventually transmitted across cable 244b to TPU
242b, wirelessly to TPU 246a, and across data cable 244a to the direction
control logic of downhole device 115, thus providing control data for
directional control of drill bit 116.

[0029]FIG. 3 shows a block diagram of a TPU 400, suitable for use as TPUs
242 and 246 of FIG. 2, in accordance with at least some illustrative
embodiments. TPU 400 includes radio frequency transceiver (RF Xcvr) 462,
which includes RF transmitter (RF Xmttr) 416, RF receiver (RF Rcvr) 418
and processor interface (Proc I/F) 414. The output from RF transmitter
416 and the input to RF receiver 418 both couple to antenna 466, which
transmits RF signals generated by RF transmitter 416 (and sent to other
TPUs), and receives RF signals processed by RF receiver 418 (received
from other TPUs). Processor interface 414 couples to both RF transmitter
416 and RF receiver 418, providing data received from processing logic
464 to modulate the RF signal generated by RF transmitter 416, and
forwarding data to processing logic 464 that is extracted from the
received RF signal by RF receiver 418. In this manner, RF transceiver 462
implements at least part of a data retransmission function between the RF
signal present on antenna 466 and a data signal present on data cable 244
(described further below). In at least some illustrative embodiments, the
interface between processor interface 414 and transceiver interface (Xcvr
I/F) 408 of processing logic 464 is an RS-232 interface. Those of
ordinary skill in the art will recognize that other interfaces may be
suitable for use as the interface between RF transceiver 462 and
processing logic 464, and all such interfaces are within the scope of the
present disclosure.

[0030]TPU 400 further includes processing logic 464, which in at least
some illustrative embodiments includes central processing unit (CPU) 402,
volatile storage 404 (e.g., random access memory or RAM), non-volatile
storage 406 (e.g., electrically erasable programmable read-only memory or
EEPROM), transceiver interface 408 and cable interface (Cable I/F) 410,
all of which couple to each other via a common bus 212. CPU 402 executes
programs stored in non-volatile storage 406, using volatile storage 404
for storage and retrieval of variables used by the executed programs.
These programs implement at least some of the functionality of TPU 400,
including decoding and extracting data encoded on a data signal present
on data cable 244 (coupled to cable interface 410) and forwarding the
data to RF transceiver 462 via transceiver interface 408, as well as
forwarding and encoding data received from RF transceiver 462 onto a data
signal present on data cable 244. In this manner, processing logic 464,
in at least some illustrative embodiments also implements at least part
of a data retransmission function between an RF signal present on antenna
466 and a data signal present on data cable 244.

[0031]TPU 400 also includes power source 468, which couples to batteries
470. Batteries 470 provide power to both processing logic 464 and RF
transceiver 462, while power source 468 converts kinetic energy (e.g.,
oscillations of the drill string or the flow of drilling fluid) into
electrical energy, or thermal energy (e.g., the thermal difference or
gradient between different regions inside and outside the drill string)
into electrical energy, which is used to charge batteries 470. Other
techniques for producing electrical energy, such as by chemical or
electrochemical cells, will become apparent to those of ordinary skill in
the art, and all such techniques are within the scope of the present
disclosure. In other illustrative embodiments (not shown), electrical
energy can be provided from the surface and transferred to the TPUs using
wireless energy transfer technologies such as WiTricity and wireless
resonant energy link (WREL), just to name a few examples.

[0032]FIG. 4A shows a drill pipe joint 200 joining two drill pipes using a
pin and box configuration, each drill pipe joint section including a
wireless communication assembly constructed in accordance with at least
some illustrative embodiments. Pin 202 of drill pipe 240b includes
wireless communication assembly 450b, and attaches to box 204 of drill
pipe 240a via threads 206. Box 204 similarly includes wireless assembly
450a. Each wireless communication assembly 450(a and b) includes a
radiotransparent housing 452, a TPU 400 and a radiotransparent spacer
454. Each TPU 400 couples to a corresponding data cable 244, which
includes one or more conductors 245 that are protected by external cable
armor 243, and which attaches to the drill pipe's inner wall as
previously described. Alternatively, one or more optical fibers 245, or
combinations of electrical conductors and optical fibers 245, may be
used, and all such data transmission media and combinations are within
the scope of the present disclosure.

[0033]The radiotransparent material used in both the spacers and housings
results in little or no attenuation of radio frequency signals
transmitted and received by the TPUs as the signals pass through the
spacer and housing, as compared to the attenuation of the RF signal that
results as it passes through the metal body of the drill pipe and through
the drilling fluid flowing within the drill pipe. In the example of FIG.
4A, each radiotransparent spacer 454 attaches to its corresponding
radiotransparent annular housing 452 via an inner thread 456. Each
radiotransparent spacer 454 further includes an outer thread 458, which
mates with a corresponding thread along the inner wall of each of pin 202
and box 204. Thus housing 452a attaches to spacer 454a via threads 456a,
which in turn mates with box 204 via threads 458a, securing the spacer
and housing to the upper end of drill pipe 240a. Housing 452b and spacer
454b are similarly secured (via threads 456b and 458b), to pin 202 at the
lower end of drill pipe 240b. Although the radiotransparent spacers and
the housings are described and illustrated as attached to the drill pipe
using threads, those of ordinary skill in the art will recognize that
other techniques and/or hardware may be used to attach these components.
For example, screws, press fittings and C-rings could be used, and all
such techniques and hardware are contemplated by the present disclosure.
Those of ordinary skill in the art will also recognize that although an
annular housing is used in the embodiments presented herein, other
geometric shapes may be suitable in forming the housing, and all such
geometries are also contemplated by the present disclosure.

[0034]Each spacer, together with its corresponding housing, operates to
protect and isolate its corresponding TPU from the environment within the
drill pipe, and provides a path for RF signals to be exchanged between
the TPUs with little or no attenuation of said RF signals. Although the
gap between the ends of the two wireless communication assemblies 450a
and 450b (i.e., between the spacers and housings of each of the two drill
pipes, shown exaggerated in the figures for clarity), and/or the gap
between each spacer and the housing, may allow drilling fluid into the
path of the RF signal, the level of attenuation of the RF signal that
results can be maintained within acceptable limits for a given
transmission power at least by limiting the size of the gaps. In at least
some illustrative embodiments, such as shown in the example of FIG. 4B,
at least some of the gaps (e.g., between the spacer and the housing) are
eliminated through the use of a single piece radiotransparent housing
that does not require a separate spacer. In other illustrative
embodiments, the level of attenuation of the RF signals in the gap
between the ends of wireless communication assemblies 450a and 450b may
be reduced through the use of additional radiotransparent spacers (made
of either rigid or flexible materials) positioned within the gap (not
shown).

[0035]FIG. 5 shows detailed cross-sectional views of a wireless
communication assembly 450, constructed in accordance with at least some
illustrative embodiments. A lateral cross-sectional view is shown in the
center of the figure, a top cross-sectional view AA is shown at the top
of the figure as seen from the end of the assembly extending into the
drill pipe (see FIG. 4B), and a bottom cross-sectional view BB is shown
at the bottom of the figure as seen from the end of the assembly closest
to the open end of the drill pipe (see FIG. 4B). Continuing to refer to
FIG. 5, wireless communication assembly 450 includes annular housing body
451 and annular housing cover 453, which together to form
radiotransparent annular housing 452 of FIG. 4B. Annular housing cover
453 includes one side of threads 158 of FIG. 4B, used to attach assembly
450 to the drill pipe. Annular housing cover 453 covers and seals various
cavities within annular housing 453 that house the various components of
wireless communication assembly 450. These components together form TPU
400, and include wireless transceiver 462, processing logic 464 (coupled
to both wireless transceiver 462 and data cable 244), antenna 466
(coupled to wireless transceiver 462), batteries 470 (coupled to each
other, and to both wireless transceiver 462 and processing logic 464 to
which they provide power), and power source 468 (e.g., a generator or a
wireless energy transfer power source), which provides power to recharge
batteries 470.

[0036]In at least some illustrative embodiments, power source 468 is a
kinetic microgenerator that converts drill string motion and oscillations
into electrical energy. In other illustrative embodiments, power source
468 is a kinetic microgenerator that converts movement of the drilling
fluid into electrical energy. In yet other illustrative embodiments,
power source 468 is a thermal microgenerator that converts thermal energy
(i.e., thermal gradients or differences within and around the drill
string) into electrical energy. Many other systems for providing
electrical energy for recharging the batteries and providing power to
wireless communication assembly 450 will become apparent to those of
ordinary skill in the art, and all such systems are within the scope of
the present disclosure.

[0037]As can be seen in the illustrative embodiment of FIG. 5, components
are positioned in voids provided within annular housing body 451. The
voids are of sufficient depth so as to allow small rectangular components
(such as wireless transceiver 462, processing logic 464 and each of the
batteries 470) to be positioned within annular housing body 451 without
mechanically interfering with annular housing cover 453. Other larger
components, such as antenna 466 and power source 468, are shaped to
conform to the curve of annular housing body 451. FIG. 6 shows an example
of how antenna 466 may be mounted to conform to such a curve, in
accordance with at least some illustrative embodiments. Antenna 466 is an
example of a 2.450 GHz, spike antenna designed to be used together with a
wireless communication assembly mounted within a 51/2'' full hole (FH)
drill pipe joint. The use of 2.450 GHz as the center frequency of the RF
transceivers allows wireless transceiver 462 to be chosen from a broad
selection of small, low-power, inexpensive and readily available
transceivers (e.g., the RC2000/RC2100 series RF modules manufactured by
Radiocrafts) that are designed with an operating frequency range within
the industrial, scientific and medical (ISM) band defined between 2.400
GHz and 2.500 GHz. This broad selection of transceivers is due, at least
in part, to the extensive use of this band in a large variety of
applications and under a number of different communication standards
(e.g., Wi-Fi, Bluetooth and ZigBee). The use of this frequency further
allows for higher data rates than current systems, easily accommodating
data rates in excess of 1,000,000 bps. The use of this frequency also
allows for the use of any type of antenna suitable for use within the ISM
band (e.g., spike antennas and loop antennas) within the limited amount
of space of annular housing body 451, due to the relatively small
wavelength of the RF signal (and the corresponding small dimensions of
the antenna). Nonetheless, those of ordinary skill will recognize that
other components operating at other different frequencies may be suitable
for use in implementing the systems, devices and methods described and
claimed herein, and all such components and frequencies are within the
scope of the present disclosure.

[0038]Continuing to refer to FIG. 6, antenna 466 couples to wireless
transceiver 462, which is mounted on one side of a flexible dielectric
substrate 472 manufactured of Polytetrafluoroethylene (PTFE, sometimes
referred to as Teflon®) that is radiotransparent to RF signals in the
2.400-2.500 GHz range. Antenna 466 is made of a flexible material as
well, allowing it to conform to the curvature of annular housing body
451, as shown by the dashed outline of the right end of substrate 472 in
FIG. 6. Processing logic 464 is also mounted on substrate 472 and coupled
to wireless transceiver 462 via interconnect 463. A shield plate 474 is
mounted on the side of the substrate opposite wireless transceiver 462
and processing logic 464. In at least some illustrative embodiments, the
shield plate is a thin flexible conductor that, together with the
flexibility of substrate 472, allows wireless transceiver 462 and
processing logic 464 to be positioned as shown in FIG. 5, conforming to
the curvature of annular housing body 451. In other illustrative
embodiments, the shield plate is more rigid and has fixed bends (as shown
in FIG. 6 by the dotted outline of the left end of substrate 472) to also
allow the positioning of the components as shown in FIG. 5.

[0039]As previously noted, transmitted RF signals suffer significant
attenuation when passing through the metal drill pipe and through the
drilling fluid within the drill pipe. This is due to the fact that when
an RF signal passes through a material, the higher its conductivity (or
the lower its resistivity), the higher the amount of energy that is
transferred to the material, resulting in a corresponding decrease or
attenuation in the magnitude of the RF signals that reach the RF
receiver. Thus, the attenuation of the RF signal that reaches a receiver
can be minimized by reducing the amount of RF energy that is propagated
through materials with high conductivity. Such a reduction can be
achieved or offset by: 1) reducing the distance that the signal traverses
between the transmitter and the receiver; 2) using antennas at the
transmitter, receiver, or both that provide additional gain to the
transmitted and/or received signals; and 3) using antenna configurations
and geometries that result in radiation patterns that focus as much of
the propagated RF signal as possible through materials positioned between
the transmitter and receiver that are transparent (i.e., have a very low
conductivity, or are non-conducting and have a low dielectric dissipation
factor) within the frequency range of the propagated RF signals. For
example, some high temperature fiberglass plastics (i.e.,
fiber-reinforced polymers or glass-reinforced plastic), with working
temperatures of 572° F.-932° F. and dielectric dissipation
factors of 0.003-0.020, are suitable for use with at least some of the
illustrative embodiments, as are some silicon rubbers with comparable
dielectric properties.

[0040]The use of wireless data transmission at the pipe joints and wired
data transmission within a drill pipe, as previously described and shown
in FIG. 2, reduces the transmission distance to that of the distance
between the TPUs described and shown in FIGS. 4A and 4B, or more
specifically between the antennas of the TPUs, shown and described in
FIGS. 4A, 4B and 5. Multi-element antennas (not shown) may be used in at
least some embodiments to increase the gain at the transmitting and/or
receiving antennas. FIG. 7 shows an example of a radiation pattern that
focuses the radiated energy within the radiotransparent material. The
"doughnut" shaped radiation pattern results in at least part of the
region of maximum intensity of the radiated signal being propagated along
the z-axis within the annular region between two adjacent antennas (e.g.,
the region between TPUs 400a and 400b of FIG. 4A, including
radiotransparent spacers 454a and 454b, as well as the gap between the
spacers). As can be seen in FIG. 7, radiation patterns that maximize the
radiated energy propagated through the radiotransparent material include
patterns wherein the plane containing the magnetic field vector (or
"H-plane") is parallel to the z-axis (corresponding to the central axis
of annular housings 452a and 452b of FIG. 4B), and thus parallel to the
propagation path of the RF signal.

[0041]By focusing the beam along a path between the two antennas that is
filled primarily or entirely with a radiotransparent material, the RF
signal transmitted along the signal propagation path between the two TPU
antennas is received with little or no attenuation by the receiving TPU.
Also, by curving the antenna into a loop as shown in FIG. 7, the
transmitting and receiving antennas are substantially insensitive to
differences in their relative angular or radial orientations (compared to
other antennas such as, e.g., straight dipole antennas), due to the
general uniformity of the RF radiation pattern illustrated in the figure.
As a result, the magnitude of the signal present at the receiving TPU is
substantially independent of the relative radial orientations of the
transmitting and receiving TPU antennas. This orientation insensitivity,
coupled with the wireless communication link used between TPUs, allows
drilling pipes to be connected to each other during drilling operations
without any additional or special procedures or equipment, relative to
those currently in operation.

[0042]Additionally, by improving the magnitude of the RF signal present at
the receiving TPU, less power is needed (compared to at least some other
existing downhole communication systems) both to transmit the RF signal
and to amplify and process the received RF signal, for a given desired
signal to noise ratio at the receiving TPU. This lower power consumption
rate allows the TPU to operate for a longer period of time without having
to shut down and allow the power source to recharge the batteries. In
systems that do not incorporate a power source, the TPU can operate for a
longer period of time without having to trip the drill string in order to
charge or replace the TPU batteries (or replace a pipe segment with dead
TPU batteries). Also, by improving the power efficiency of the system,
higher data rates may be achieved (within the bandwidth limits of the
system) for a given level of power consumption relative to existing
systems (based on the premise that the higher operating frequencies
needed for higher data transmission rates incur higher TPU power
consumption).

[0043]FIG. 8 shows a method 800 for wireless transmission of data across a
joint mechanically connecting two drill pipes within a drill string used
for drilling operations, in accordance with at least some illustrative
embodiments. Data is received across a data cable in a first drill pipe
by an RF transmitter in the same drill pipe (block 802). The received
data is used to modulate an RF signal (block 804), which is transmitted
from a first antenna within the first drill pipe through radiotransparent
material, propagating the RF signal to a second antenna within a second
drill pipe along a path that is parallel to an H-plane associated with at
least part of one or both of the two antennas (block 806). In at least
some illustrative embodiments, the RF signal is further transmitted
across one or more gaps in the radiotransparent material, which contains
drilling fluid that is made to circulate through the drill string (not
shown). The modulated RF signal present at the second antenna is received
by an RF receiver within the second drill pipe (block 808), which
extracts the data from the modulated RF signal (block 810). The extracted
data is transmitted to across data cable within the second drill pipe to
a second device within the same, second drill pipe (block 812), ending
the method (block 814). In at least some illustrative embodiments, the
method is used to monitor and control operations of a drill string that
is part of a drilling rig such as that shown in FIG. 1.

[0044]The above discussion is meant to illustrate the principles of at
least some embodiments. Other variations and modifications will become
apparent to those of ordinary skill in the art once the above disclosure
is fully appreciated. For example, although the embodiments described
include RF transceivers that perform the modulating and demodulating of
the transmitted and received RF signals respectively, other embodiments
can include RF modules that only up-convert and/or down-convert the RF
signals, wherein the processing logic performs the modulation and/or
demodulation of the RF signals (e.g., in software). Further, although a
simple single bus architecture for the processing module is shown and
described, other more complex architectures with multiple busses (e.g., a
front side memory bus, peripheral component interface (PCI) bus, a PCI
express (PCIe) bus, etc), additional interfacing components (e.g., north
and south bridges, or memory controller hubs (MCH) and integrated control
hubs (ICH)), and additional processors (e.g., floating point processors,
ARM processors, etc.) may all be suitable for implementing the systems
and methods described and claimed herein. Also, although the illustrative
embodiments of the present disclosure are described within the context of
petroleum well drilling, those of ordinary skill will also recognize that
the methods and systems described and claimed herein may be applied
within other contexts, such as water well drilling and geothermal well
drilling, just to name some examples. Additionally, the claimed methods
and systems are not limited to drill pipes, but may also be incorporated
into any of a variety of drilling tools (e.g., drill collars, bottom hole
assemblies and drilling jars), as well as drilling and completion risers,
just to name a few examples. It is intended that the following claims be
interpreted to include all such variations and modifications.